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Data from literature as well as the results of the author's investigations on the genotoxic and carcinogenic effects of sodium nitrite (SN) are presented. Carcinogenicity of SN detected in animal experiments proved to be connected with the formation of nitroso compounds from endogenous nitrosable precursors. Sodium nitrite possessed the transforming and promoting effects in the cell cultures as well as the mutagenic effects in the bacterial systems where predominant effect of SN as compared with N-nitrosodimethylamine (NDMA) was registered. The prolonged pretreatment with SN amplified the liver DNA damage in rats in case of NDMA endogenous synthesis.

A combined administration of cis-dichlorodiaminoplatinum (DDP) and phenobarbital increases the activity of nonspecific oxidases, decreases the toxic effect of DDP especially its nephrotoxic action, but does not decrease the antiblastic action of DDP in rats. On the basis of experimental data the optimum regime of DDP repeated administrations is suggested.

After the long-term administration of doxilane-diolane, cresacin, antioxidant S-1 and fluorine varnish to mongrel albino rats and mice no difference in the level of spontaneous tumours both in the control and experimental groups of animals was observed. It is concluded that these drugs possess no carcinogenic activity.

Data obtained from the 10 year study of the spontaneous neoplasm incidence in mongrel mice and rats (males and females) from the colony of the R.E. Kavetskiĭ Institute for Oncology Problems are adduced. Spontaneous carcinogenesis was at an average 1:8 in mice (132 tumours per 1120 mice) and 1:3 in rats (93 tumours per 335 rats). Tumours of mammary glands and of pituitary prevailed in rat females.

It is established that the preparation K-2-9 being administered in combination with cis-dichlorodiaminoplatinum (DDP) lowers the DDP toxic effects, in particular nephrotoxicity and enterotoxicity, increases the activity of the enzymes participating in microsomal liver oxidation, the activity of kidney transamidinase, the quantity of SH-groups of the liver and kidney tissue, intensifies the antitumour effect of DDP.

The intravenous or intraperitoneal injection of amidopyrine and sodium nitrite to rats induces liver necrosis caused by endogenic synthesis of carcinogenic N-nitrosodimethylamine (NDMA). Ascorbic acid, which inhibits this synthesis when injected intravenously, phenobarbital, which is an inductor of enzymatic decomposition when injected intraperitoneally, prevented the formation of necrosis.

The combined administration to mice of N-nitrosodimethylamine (NDMA) in drinking water and of benz(a)pyrene (BP) in skin applications induces mainly skin tumours and the use of BP in food--stomach tumours. The skin application of BP prevents the development of tumours after NDMA administration. The combined action of these carcinogens reduces the latent period of tumour incidence, lowers the induction of BP-hydroxylase and the activity of N-demethylase of NDMA.

The effect of complex-forming sorbent K-2-9 on cisplatin toxicity was studied experimentally. Simultaneous treatment with the preparations was shown to lower the nephro- and gastroenterotoxicity of cisplatin did not detract from the antitumor effect of cisplatin.